Where Chauvet Cave has been called the 'Sistine Chapel of the Stone Age'. The original drawings are too sensitive to visit, but here we can see a perfect replica of the earliest art humans ever created.

♪♪ When you look at this marvelous wall, you see all of the major animals of the Stone Age world depicted.

You've got reindeer and mammoths, big cats.

But the horse seems to play the most prominent role.

Now, I thought that was in my imagination, but then I saw something just down there that convinced me.

There it is.

They've saved this alcove like an altar for a single animal.

And it's a horse.

Horses are the stars of Ice Age art.

Our ancestors drew them perfectly.

And more than any other animal.

DR. FLOSS: This will be the first horses in the cave.

They depicted this horse with their fingers.

THOMPSON: Ya.

German archaeologist Harold Floss has studied Chauvet since its discovery in the 1990s.

DR. FLOSS: Horses were important for the nutrition of these people.

They hunted horses and they knew horses very well.

But I am sure that nutrition is not all.

These guys had a spiritual connection with these animals.

THOMPSON: It must have been the case with these people that everything has a spirit.

The features of the landscape, the creeks and rivers, everything carries a spirit.

DR. FLOSS: Exactly. And animals too.

THOMPSON: Ya.

DR. FLOSS: But you are killing these animals... ♪♪ ...and there may rise a problem, which you have to resolve.

♪♪ And this is, in my point of view, one of the main reasons Palaeolithic art is existing.

THOMPSON: Once, we hunted horses.

♪♪ But what we left on the wall of this cave hinted at a new future.

A time when our bond with this sacred animal would be transformed.

♪♪ At the end of the Ice Age, grasslands became forests.

♪♪ Horses evolved in the Americas.

But there, they disappeared completely.

Only a handful survived on the grassland steppes of Central Asia.

And that is where humans domesticated the wild horse 6000 years ago.

We know this because we've discovered their ancient home.

A place called Botai, in Kazakhstan.

♪♪ ♪♪ On the fragments of pottery they left behind, scientists discovered the remains of milk.

Horse milk.

And you can't milk a wild horse.

[ Neighing ] ♪♪ We had harnessed horsepower.

♪♪ For humans who traveled by foot, riding changed everything.

We discovered speed and conquered distance.

Now, the horse shaped our world.

And with time, we shaped the horse for our needs.

New breeds helped humans survive in new environments.

And eventually, horses took us to some truly extreme places.

♪♪ Places like this.

♪♪ Yakutia, in Russia's Arctic.

♪♪ Here, extreme cold has created a very special horse.

But to find it takes a thousand-mile journey from the nearest airport.

♪♪ ♪♪ THOMPSON: I've come all this way to see a man called Alexei.

Where I come from, we'd call him a cowboy, and we'd call this a ranch.

But it's not cows that Alexei is running.

It's horses.

In fact, he has one of the biggest herds in all of Yakutia.

300 horses in the coldest place that humans inhabit.

And I want to see how he does it.

♪♪ Well, there's Alexei.

He's just bringing a herd of yearlings in.

He's the man we've come to meet.

Alexei tells me his people came here eight centuries ago.

They fled violence in Mongolia, riding north into the Siberian forest.

They were completely reliant on their horses for transport and for food.

Today, little has changed.

It's so cold. It's so cold.

I mean, I knew it would be cold, but nothing really prepares you.

Under the midday sun, it warms to minus 40.

Overnight, it will fall to minus 50.

Even under all this frost, these horses seem content.

But the humans need a break.

Alex and his father tell me their ancestors had no intention of settling in the coldest place on Earth.

But I'm curious.

What kind of horse can survive that?

♪♪ [ Calling ] The humans who live here use technology to survive.

Warm clothing.

Shelter.

But not horses.

They had to evolve -- their bodies had to change.

♪♪ In this intense cold, Yakutian horses have gotten smaller, their legs shorter.

♪♪ The shape Nature chose here isn't elegant... but it works.

During the long winter, they reduce their metabolism.

Yet they stay on their feet.

This unique behavior is called standing hibernation, and no other horses do it.

It's a textbook example of natural selection.

Without it, Yakuts may never have survived in this environment.

It's amazing.

An Arctic horse that made an Arctic people.

But really, shaping a special breed for a special place isn't uncommon at all.

Every horse culture creates its own horses.

♪♪ ♪♪ Some love the cold.

And some love the heat.

Arabia.

One of the hottest places on Earth.

A world without water.

♪♪ But even here, you find people.

I've come to the Arabian Desert to meet a remarkable breed.

A horse that makes it possible to survive where no human could survive alone.

♪♪ This is the homeland of the Bedouin.

Beyond the oases, the Bedouin could only survive by constantly moving.

So for thousands of years, they have lived on horseback.

[ Conversing in Arabic ] The endless migrations of the Bedouin have shaped a special kind of horse.

♪♪ A desert breed.

The Arab.

The Arab horse is famous for being hardy, spirited and fast.

♪♪ No matter how hot it gets, these horses just love to run.

♪♪ ♪♪ ♪♪ Arabs are called 'hot blood', and most people think that refers to their character, their personality.

But when I think of the features that -- Oh, come over here -- the features that these men prize in an Arab horse, they're really about dealing with the heat.

So these high fine ears, this fine facial structure, these big nostrils and then even the high tail there.

All of these features are the architecture of a horse that's built to shed heat in a hot environment.

And I think that's why this horse is having a much better time then I am in this climate.

Aren't you? Yeah.

Arabs are one of the oldest breeds.

They've been carrying humans through these scorching deserts for at least 2,000 years.

Like Yakutians in the Arctic, this is an extreme horse... created by an extreme world.

♪♪ After a long day in the saddle, we're all sore.

But the horses seem just fine.

These are tough animals.

Without them, we wouldn't be here.

Even though we're out of the saddle, we're still talking about horses.

My guides tell me a Bedouin legend.

They call a mare Banat er rih: 'daughter of the wind.'

Their horses move like a storm.

That is why they give us the power of flight... without wings.

♪♪ It's not hard to see why the Bedouin believe God made horses just for them.

♪♪ But science tells us, this breed is simply Nature's answer to an extreme environment.

Bred for the desert, Arab horses just happen to be absolutely gorgeous.

♪♪ But in different parts of the world, you find completely different horses.

Like Icelandics... and Fjords.

Horses with a 2,000-year history of putting up with weather in Scandinavia.

With a shape like this, you'd think these were little ponies.

You'd be wrong.

♪♪ Weather shaped horses.

But so did we.

Breeds were created for some very special jobs.

The beautiful Friesian, bred to carry 250 kilos of armored knight into battle.

Bred today...for looks.

♪♪ ♪♪ Or the Drum horse.

Created... just to carry the regimental drums of the Queen's bodyguard.

♪♪ This one's a star.

The Quarterhorse.

With the power to turn on a dime.

And accelerate.

♪♪ ♪♪ Aristocratic breeds.

Prized by nobility.

Like the Warmblood.

Once, a jumper in battle.

Now, a jumper for sport.

♪♪ But one horse above all became the very definition of horsepower.

♪♪ The Belgian.

A ton of pulling power.

A Belgian can reach 7 feet in height.

And yet, they're one of the gentlest breeds.

In the age of horsepower, if there was a job for the horse, there was a horse for the job.

From giants... to miniatures.

♪♪ Our ancestors left us with an astonishing diversity of horses.

And we found a place for them in every part of human life.

♪♪ It's easy to forget how much our world once revolved around the horse.

♪♪ But go back in time, and horses are everywhere.

♪♪ Before humans knew we could ride horses, think of the impression it made when we first saw a rider.

I mean, I think that's the origin of the myth of the centaur.

The body of a horse, the torso and the head of a man.

A completely impossible creature... but there it was in front of us.

♪♪ Looking through the collections at the British Museum, it really strikes me that almost every time you see a horse in ancient art, it's a horse at war.

And not how I expected.

Instead of riding horses, we were behind them... in chariots.

♪♪ Look at this.

This is the Assyrian king Ashurbanipal standing upright in his chariot.

To me, this doesn't make any kind of sense, because in a world without roads, how is it even possible to stand in a chariot, racing around the battlefield?

I mean, there you are bouncing along, trying to shoot your bow and arrow and you're a huge target for the enemy.

But here's the proof.

Somehow the chariot was a game changer.

We just don't really understand how.

The only way to really know how chariots worked then... is to build one now.

♪♪ In this English workshop, we're reconstructing a perfect copy of one of the oldest chariots ever discovered.

The original was built over 3,000 years ago, in China.

♪♪ After months of work, it's finally finished.

HURFORD: And there we are.

THOMPSON: It's ready to be tested.

But that...takes someone with some unusual skills.

Mike Loades.

Mike's spent his life studying how horses changed history on the battlefield.

And today, he's going to see our chariot for the first time.

-THOMPSON: Are you ready? -LOADES: I'm ready.

Let's have a look.

Wow.

THOMPSON: There it is. Is this how you imagined it?

LOADES: No, it's so much more. It announces itself.

♪♪ THOMPSON: It may be impressive, but our experimental chariot is missing the key ingredient.

Horsepower.

MAN: Whoa. Steady. Steady.

THOMPSON: For our test, Mike is using specialized chariot horses.

And they're tiny.

LOADES: Chariot horses are surprisingly small.

You couldn't ride horses like this into battle.

But two horses pulling a wheeled vehicle could carry a load far in excess than the weight they could carry on their backs.

Whoa. Easy.

♪♪ They had to have tremendous stamina for running all over the battlefield, and going on campaign.

They had to have strength to pull those men on the chariot.

They had to have spirit.

THOMPSON: These ponies also have to run in unison -- one stumble, and the whole chariot goes down.

Mike makes it look easy, but I have a feeling it isn't.

I'll give this a try. -LOADES: Yeah, up you come.

-THOMPSON: Ok. -LOADES: That's it.

THOMPSON: Now what are you doing?

One foot ahead of the axle, one foot behind the axle?

LOADES: Yeah. You've obviously got that pole in an emergency to grab onto.

Walk on, lads. Giddyup.

There you go.

There you go. You all right?

Yeah, you're doing pretty well, I think.

THOMPSON: I cannot imagine handling weapons in this situation.

All I'm doing is standing in one place.

LOADES: Going around a corner.

THOMPSON: I'm going to try to let go with my hands.

LOADES: Stand up.

Yay, surfing. Going around to the right.

THOMPSON: I was right -- standing is hard.

But maybe that's not what you're supposed to do.

♪♪ LOADES: Whoa.

THOMPSON: How's that going?

LOADES: Well, that was very interesting.

I mean, there's no doubt about it, it's a lot of fun to stand up.

It's the glamorous Hollywood idea of what you do in chariots.

And it's perfectly doable.

But then I was thinking well, why the low rail?

So, I thought well, it's, it's, it's inviting me to kneel.

So can I drive kneeling?

Yeah, actually, that's really quite comfortable.

The light bulbs go off.

This -- this just fits.

I'm completely secure.

Can I shoot from here? I'm sure I can.

We've got to test that.

But that's what's so exciting.

The chariot speaks to you.

It tells you how it wants you to use it.

♪♪ If you took squadrons of chariots against an infantry army, you could have run circles round them, you could've pinned them down, and they can't get you.

♪♪ THOMPSON: Mike's convinced me.

If you know what you're doing, chariots can be deadly.

♪♪ Chariots ruled the battlefield for a very long time.

But then, a new way of harnessing horsepower emerged and a new kind of horse warrior replaced the chariot team.

Horse archery.

A man on a horse with a bow and arrow.

You put thousands of those in the field and no chariot army can compete.

LOADES: You can spin a horse so much more easily than you can a chariot.

You know, I can come around and do this.

I can run around you and then... The speed of the horse and the speed of the shooting.

It's absolutely a teamwork.

I mean you actually do become a centaur.

From the waist down, you're a horse.

From the waist up, you're an archer.

You become the mythical centaur.

There was a key change that had to happen with horses to enable the horse archer.

Horses had to get bigger.

They had been selectively bred with more bone.

With more muscle.

That became the riding horse.

Once the ridden horse comes onto the battlefield and you have the horse archer, then you've really got an extremely versatile warrior.

A single horse can go places that a chariot can't.

Once the horse archer entered the battlefield, then the days of the chariot were numbered.

And that is the beginning of a long and tragic story for the horse.

The carnage, the loss of life, the tragedy of horses in the service of man's wars.

♪♪ THOMPSON: For thousands of years, horses were invaluable on the battlefield.

Not anymore.

Today we cherish horses for different reasons.

♪♪ This newborn foal is a Thoroughbred.

And it's carrying a huge weight of expectations on its little shoulders.

♪♪ ♪♪ ♪♪ ♪♪ Among the breeds, Thoroughbreds are specialists.

♪♪ We created them for one purpose: to run faster than any other horse alive.

♪♪ ♪♪ ♪♪ All Thoroughbreds belong to one tiny family of horses.

♪♪ Incredibly, every living one is a descendant of one of three stallions, who lived 200 years ago.

The Stud Book is closed.

DR. HILL: The Thoroughbred has been a closed Stud Book since the early 1800s, when it was determined that no further input from exotic gene pools would improve the breed.

And so it was said that this breed is now 'thoroughly bred'. And that's where the term 'Thoroughbred' comes from.

THOMPSON: Emmeline Hill is an Irish geneticist.

Several years ago, working with the DNA of Thoroughbred racehorses, Emmeline had a breakthrough.

She discovered a kind of genetic recipe for speed.

She calls it the 'Speed Gene'. DR. HILL: For hundreds of years, I suppose, people have used pedigrees to try to figure out if it's a sprint type pedigree or a pedigree with more stamina.

We can now take the guesswork out of that.

We're able to actually look inside the DNA and identify those genes that are contributing to an elite athlete.

THOMPSON: Jim Bolger raises some of Ireland's fastest horses.

♪♪ When Emmeline discovered the Speed Gene... Jim took the leap.

He let her use the test on his elite Thoroughbreds, hoping to spot a special horse.

DR. HILL: We'll send you the results in advance.

They're ready now.

BOLGER: We're not going to have a top horse every year.

It's a game of chance, and it's very high risk, but we only need one.

THOMPSON: With Emmeline's help, he found the one.

A stallion called Dawn Approach.

At two years old, he emerged on the European scene as an unbeatable racehorse.

After just one season, Jim sold his champion for a fortune.

♪♪ Today, Dawn Approach has run his last race.

His new owner sells his sperm.

Each insemination is worth $50,000.

♪♪ In his lifetime, he will father thousands of foals.

♪♪ Emmeline's discoveries are helping us squeeze every last ounce of speed from Thoroughbreds.

But with only a tiny few allowed to pass on their genes, the genetic diversity of this breed is getting even smaller.

DR. HILL: Limited genetic diversity could potentially be a problem.

You have a very high-level of inbreeding, particularly when you have a stallion of high value, and therefore has very large numbers of progeny.

The genetic health of the population could be in jeopardy.

It's the unknowns that are always the problem.

THOMPSON: As we take breeding to incredible extremes, we're getting incredible results.

But there's a fine line between breeding... and inbreeding.

♪♪ The Thoroughbred is a human invention.

Such a delicate animal wouldn't survive in the wild.

Leave it to nature, and you get a very completely different horse.

They say there are no truly wild horses.

♪♪ Except for these.

♪♪ A mythical horse, hanging on in an impossible place.

♪♪ The horses of Sable Island.

♪♪ Their ancestors were left on this sliver of sand off Canada's East Coast at least 40 generations ago.

How they got here, no one knows.

Settlers?

Shipwrecks?

Whatever their story, today, they belong to no one.

♪♪ Few get permission to visit.

I'm very lucky to be on this plane with biologist Phil McLaughlin.

PILOT: Estimating landing on the beach in seven minutes.

♪♪ THOMPSON: Phil and I share the same question.

What happens to horses when they return to the wild?

THOMPSON: So this is a situation where you have horses who we used to shape, now being shaped by this natural environment.

I mean, at what point do we start calling them wild horses?

McLAUGHLIN: I call them wild horses.

There's not been any interactions with humans other than what -- what we're doing right now.

Looking at them.

It actually still amazes me how well they do.

♪♪ THOMPSON: Phil can go right up to some of the adult horses and they really aren't bothered at all by his presence.

They're more curious of him than anything.

As far as these horses are concerned, human don't exist.

Now, they live in partnership with a different animal: seals.

♪♪ Every winter, half a million grey seals crowd onto the sands to give birth.

And this huge gathering of sea mammals keeps the horses alive.

McLAUGHLIN: So we have seals coming onto the island for weeks where they're pupping, they're mating... and while they're here, they're fertilizing the grasses.

The influx of nutrients is -- is quite impressive.

And the horses are responding to this.

♪♪ THOMPSON: It's a remarkable connection between two mammals who couldn't be less alike.

The seals bring nutrients to these barren dunes, and the horses feast on the grass.

A food cycle that nourishes over 500 horses on Sable today.

But within that population, a new horse is emerging.

A tougher animal that has to fight to survive.

Phil takes me to the far eastern end, where there is no standing water.

♪♪ The horses here are forced to dig for a drink.

McLAUGHLIN: Every horse here has to dig down, paw, get the water back up, drink.

They're going to take 20 minutes, at least.

Whereas, you go to the other side of the island, a whole band will come in to the freshwater pond.

They'll be gone in 7-8 minutes. -THOMPSON: Wow.

McLAUGHLIN: And these horses here, I always think of them as being subject to much more strife and competition.

So they're always on the watch.

You'll see bands line up over in the hills there waiting for their chance.

And the hierarchies that you see in the social groups, it's much more clear out here.

♪♪ THOMPSON: There was a little bit of a competition.

One of the stallions was -- was kind of pawing at the other male, as if to say 'Get away from my water hole'. McLAUGHLIN: Exactly. That's it.

It's an uneasy lifestyle here, and these horses don't even know what it's like on the west side.

They've never been there.

They've lived their whole life here.

THOMPSON: On Sable, it's Darwin's world.

Natural selection is shaping the horse once again.

This island shows us horses can return to the wild.

They don't need us to survive.

But even today, some people can't imagine life without horses.

The prairies of Southern Alberta.

♪♪ Home of the Blackfeet.

Hundreds of years ago, the Blackfeet became a great horse nation.

That hasn't changed.

Allison Red Crow is the great-grandson of a legendary chief and warrior.

Red Crow fought his enemies on horseback.

Allison is still passing the warrior tradition on.

In a modern way.

[ Indistinct talking ] With horse racing.

RED CROW: We are modern-day warriors.

We are still on our horses, just like our forefathers were.

They were on the back of a horse every day.

♪♪ BIG TOBACCO: It's a part of the tradition, the hair anyway.

They say it gives us strength.

THOMPSON: Cody Big Tobacco is on the team.

His little brother Ian dreams of joining.

RED CROW: Keep -- keep your body to the side.

Don't be walking right here, because he'll run right over you.

Okay? So always remember that.

He's going to be hot after the race.

Look what they're doing right now.

They're busy, eh?

They're busy, they're having fun.

I tell the boys staying at home, they'll be sitting around, getting into trouble.

That's the main thing, boys.

If we can stay out of trouble, we'll be all right.

These horses they'll keep us out of trouble.

THOMPSON: These aren't the compact Spanish horses the Blackfeet once rode.

They're Thoroughbreds.

RACE ORGANIZER: You've got about ten minutes to go.

THOMPSON: These horses are fast.

RED CROW: Come on, Tyler.

THOMPSON: In Blackfeet country, they call this Indian Relay.

A race is three bareback gallops around the track.

Speed is important.

But the race is won or lost at the exchange.

Jumping off one horse and onto another.

RED CROW: Go on. Go on!

Go on!

[ Indistinct shouting ] Horses are what makes us warriors today.

You work hard enough with them and you're willing to work with them, you're gonna feed off them, you're gonna feel that strength.

You want to try him first?

BIG TOBACCO: I'll try him first.

-RED CROW: Yeah. -BIG TOBACCO: For now.

Let's try a couple jumps.

THOMPSON: Allison and Cody are working with a new horse, who's just learning the ropes.

RED CROW: Ready boys?

BIG TOBACCO: Ok, I'll try this one.

Even if he flinches. Oh.

RED CROW: Yeah, he's never had nobody running up and jumping to him eh?

But that's alright. He's going to have to learn it.

He's going to have to get used to it.

BIG TOBACCO: You see how he kind of... he's put his feet in the proper stance to take my weight.

RED CROW: Yeah.

BIG TOBACCO: And his head's coming a lot lower.

For sure.

Hey, boy, hey, boy, hey, boy.

From the first one to that one is pretty good, eh?

♪♪ For us horse racing has always been a part of our culture.

We just do it because we love it, you know?

We love horses.

♪♪ THOMPSON: A new season of racing will soon begin.

It's time for little Ian to learn the exchange.

RED CROW: You're training right now.

The main thing is just getting on the horse, doing it right.

IAN: Ok. -RED CROW: We'll take it slow.

-IAN: How's that sorrel? -RED CROW: He's good.

It won't be -- don't worry about none of them.

They're just big pups.

IAN: I wanna race, but I still can't jump up.

RED CROW: Jump, Ian jump. That's ok.

IAN: It means a lot to me.

But I'll be up there some day.

RED CROW: Jump. Kick, kick, kick, kick, kick.

Attaboy. Attaboy. That's the way to be.

Good. That's a good exercise, boys.

THOMPSON: Ian still has some growing to do before he can ride for the team.

But that time will come.

♪♪ Outside their world, the Horse Relay is virtually unknown.

But that is about to change.

RED CROW: Oh, boy, I couldn't wait to spread the news to the boys.

THOMPSON: How did the boys take it?

RED CROW: Hooo, they were just laughing and smiling and like 'Yeah.

We're going to Calgary.'

THOMPSON: Alison's been invited to compete at the Calgary Stampede.

Just four teams, all Blackfeet.

The first time ever for the Indian Relay.

RED CROW: Not in my wildest imaginations did I think I'd be running at the Calgary Stampede.

It is the event of the season.

It's like Christmastime.

THOMPSON: They call the Calgary Stampede the 'The Greatest Outdoor Show on Earth'. But it's the same ritual as always: stretch, paint, dress.